Siemens Sinumerik 840D sl Programming Manual page 241

Note
Chamfer/rounding too high
If the values programmed for chamfer (CHF/CHR) or rounding (RND/RNDM) are too high for
the contour elements involved, chamfer or rounding will automatically be adapted:
1. If MD11411 $MN_ENABLE_ALARM_MASK bit 4 is set, alarm 10833 "Chamfer or rounding
must be reduces" is output (cancel alarm).
2. The chamfer/rounding is reduced until it fits in the contour corner. This results in at least
one block without motion. At this block, the required motion is stopped.
Note
Chamfer/rounding not possible
No chamfer/rounding is performed if:
● No straight or circular contour is available in the plane
● A movement takes place outside the plane
● The plane is changed
● The number of blocks specified in the machine data that are not to contain any information
about traversing (e.g. only command outputs) is exceeded
Note
FRC/FRCM
FRC/FRCM has no effect if a chamfer is traversed with G0; the command can be programmed
according to the F value without error message.
FRC is only effective if a chamfer/rounding is programmed in the block or if RNDM has been
activated.
FRC overwrites the F or FRCM value in the current block.
The feedrate programmed under FRC must be greater than zero.
FRCM=0 activates the feedrate programmed under F for chamfer/rounding.
If FRCM is programmed, the FRCM value will need to be reprogrammed like F on change
G94 ↔ G95, etc. If only F is reprogrammed and if the feedrate type FRCM > 0 before the
change, an error message will be output.
Fundamentals
Programming Manual, 01/2015, 6FC5398-1BP40-5BA2
10.12 Chamfer, rounding (CHF, CHR, RND, RNDM, FRC, FRCM)
Motion commands
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